This invention relates to catalysts for use in hydrocarbon conversion, specifically to a modified mazzite supported catalyst impregnated with at least one metal selected from the group consisting of chromium, molybdenum, tungsten and oxides of these metals which can be used for the dehydrogenation of hydrocarbons.
Hydrocarbon conversion is especially important in the petroleum industry. In recent years, an increasingly competitive market for gasoline has developed, and profit margins on gasoline sales have steadily declined. As a result, there has been considerable interest among petroleum companies in developing processes for chemically converting gasoline into various compounds of higher economic value.
A Gasoline Conversion Unit (GCU) is a system which converts gasoline into olefins and aromatics of higher economic value such as ethylene, propylene, butene, benzene, toluene, and xylene. Propane is a major by-product from the original GCU process; however, propane from a GCU is a paraffin of low value. It is, therefore, desirable to convert the propane from the original GCU process into a more valuable olefin such as propylene.
Numerous catalytic processes for dehydrogenating propane into propylene are known today, however many of the existing techniques are ineffective under the conditions of a GCU. The majority of catalysts which are currently used for the dehydrogenation of hydrocarbons are supported noble-metal catalyst. It is well known that supported noble-metal catalyst are vulnerable to sulfur poisoning which results in irreversible catalytic deactivation. Because of the original gasoline feedstream, it is inevitable that the propane produced by the GCU process will contain a considerable amount of sulfur. Therefore, a supported noble-metal dehydrogenation catalyst, when used under GCU conditions, is likely to be ineffective because it will undergo catalytic deactivation due to sulfur poisoning.
In addition, many existing catalytic processes for dehydrogenation require the presence of steam as a diluent in the feedstream. This requirement for steam makes existing dehydrogenation processes very utility intensive and, thus, very expensive.